Thinkprogress asked:

Why would 18 Senators, including co-sponsors of the original measure, vote for a tougher pro-consumer measure in 1991, and then vote against a weaker measure in 2005? Could it be that the more than $2 million these Senators took from the credit card/banking industry in the interim made them change their mind?

We offer the following list of those senators in case our readers wish to get an answer for themselves:

Sen. Max Baucus (D-MT)
1991-1996 contributions from commercial banks: $88,900
1997-2002 contributions from commercial banks: $170,777

Sen. Joe Biden (D-DE)
1991-1996 contributions from commercial banks: $73,575
1997-2002 contributions from commercial banks: $33,675

Sen. Thad Cochran (R-MO)
1991-1996 Commercial Banks: $24,750
1997-2002 Commercial Banks: $40,100

Sen. Pete Domenici (R-NM)

Spoke in favor of D'Amato Amendment during floor debate
1991-1996 Commercial Banks: $89,120
1997-2002 Commercial Banks: $66,290

Sen. Chuck Grassley (R-IA)
1997-2002 Commercial Banks: $123,300

Sen. John Kerry (D-MA)
1997-2002 Commercial Banks: $183,102

Sen. Trent Lott (R-MS)
1991-1996 Commercial Banks: $70,575
1997-2002 Commercial Banks: $80,800

Sen. John McCain (R-AZ)
1997-2002 Commercial Banks: $235,228

Sen. Paul Sarbanes (D-MD)
1991-1996 Commercial Banks: $84,800
1997-2002 Commercial Banks: $55,800

Sen. Richard Shelby (R-AL)
1991-1996 Commercial Banks: $246,533
1997-2002 Commercial Banks: $215,600

Sen. Arlen Specter(R-PA)
Co-sponsored the 1991 D'Amato amendment
1997-2002 Commercial Banks: $105,225

Sen. John Warner (R-VA)
1997-2002 Commercial Banks: $43,800

Other Senators who voted for the D'Amato amendment, but against the Dayton bill (data on contributions from commercial banks unavailable):

Sen. Ted Stevens (R-AK)

Co-sponsored the 1991 D'Amato amendment

Sen. Conrad Burns (R-MT)

Sen. Herb Kohl(D-WI)

Sen. Pat Leahy(D-VT)

Sen. Harry Reid (D-NV)

Sen. Larry Craig (R-ID)